Process for preserving wood



Patented June 18, 1929.

UNITED STATES 1,717,888 PATENT OFFICE.

ALFRED OBERLE, or KANSAS CITY, mssounr, ASSIGNOR or ONE-HALF To THOMAS E. SCOFIELD, or KANSAS CITY, MISSOURI.

PROCESS FOR PRESERVING WOOD.

No Drawing.

This invention relates to improvements in processes for preserving wood and products therefor and the ingredients used in connection therewith, and consists primarily in the impregnation of the wood fibre with a petroleum oil having a relatively high sulphur content, this oil being chlorinated either prior to its impregnation or subsequent thereto.

Further objects of the invention lie in the utilization of a high sulphur containing crude or its derivatives which may be used separately or together, each or all of such oils having been chlorinated either prior to the impregnation into the wood fibre or afterwards.

The process is particularly adapted to the preservation of all kinds of timber lumber, including ties, piles, telephone or telegraph poles, or for any type of wood which is subjected to the attacks of fungi or bacteria or Weather conditions.

It is recognized that heretofore innumerable combinations of chemicals and natural oils or liquids have been used to prevent or retard the action of these deteriorating agents. Creosote, zinc chloride, arsenic,.copper sulphate and sodium fluorides are perhaps the most commonly recognized preservative materials. It is recognized, further, that considerable work has been done in connection with using petroleum oils, but it is thought that up to the present time no satisfactory results have been obtained by using petroleum products for this purpose. The

failure of these products is primarily due to "their lack of toxicity, flexibility in application and the expense of adding materials to improve these properties. Furthermore, cognizance is taken at this time of the work of Carleton Ellis in connection with hydrocarbon materials and his combining the same with mineral compounds for producing wood preservatives.

It is the purpose of this invention to provide a preservative material which will readily impregnate and permeate the wood fibres, supplying thereto a toxic ingredient and one which is as effective as the commonly used creosotes and one which can be supplied at a much less cost. In this connection are employed petroleum hydrocarbons having a high sulphur content such as the Lima oils of the Ohio fields, Persian oils or Mexican oils,-a typical example of the Application filed October 19, 1925. Serial m. 63,288.

latter being Panuco crude. These oils vary considerably in the gravity, viscosity, and

the percent of sulphur, although they are all notorious in the amount of sulphur con tained therein. These oils are toxic in character due to this sulphur content, but this toxicity is increased by treatment with halogen compounds such as chlorine, bromine, iodine and fluorine. Chlorine is particularly adapted to this purpose due to the fact that it readily combines with hydrocarbons. Furthermore, chlorine has a property of combining with the cell fibres as well as the cell contents of the wood besides having a marked toxicity to the wood destroying agents.

The application of these oils for Wood preservative purposes may be made in the following manner:

First: Surface application by means of brush or spray.

Secondz'The open tank treatment which consists in dipping or in prolonged bath treatment.

Third: Treatment in closed cylinders under pressure or vacuum or both.

In utilizing these methods of impregnating the wood with a preservative material, conditions will, of course, govern the proper method to be used. Where the wood is subjected to only mild conditions of deterioration, both the method and the preservative used may be mild. On the other hand, where conditions are severe such as in the case of wood paving blocks, railroad ties, marine work, where the .wood is constantly subjected to the deteriorating effect of sea water and marine life, the preservative material must be of a character to counteract any of these conditions. Where a mild preservative is required, the sulphur containing oil may be used alone or it may be cracked or subjected to distillation and the distillate recovered used as a preservative as 'it contains a. relatively high percentage of character, they may be used separately or may be introduced to the wood successively. \Vhen used in the latter manner, it is-preferable that the lighter oil be introduced first and the heavier oil afterwards. In the case where separation is made, there is produced also a gas which is also relatively toxic in character and this gas should be; used in the impregnation to impose a pressure upon the liquid, itself permeating into the wood cells and fibres. In each case, whether the distillate or residuum is used either in combination or separately and with or without a gas, increased toxicity is produced by chlorination. This chlorination, as previously mentioned, may be eifected prior to the wood treatment or subsequent to the impregnation of the wood with the oil. Chlorination of the hydrocarbons may be produced by any of the well known v methods-typical of which would be percolating the gas throughthe hydrocarbons.

Hydrocarbon oils have a particular adaptability to wood preservation in that they do not extract any already existing preservative qualities in the wood, and furthermore, penetrate more effectively due perhaps to their capabilities in dissolving resinous and gummy materials which function to retard penetration of other preservatives. ,1 In addition to this, where steam and heat treatments are used, there, is lost from the wood some of the naturally contained preservativematerials. Where these resinous and gummy materials, and also other naturally occurring preservative agents, are attackedby a hydrocarbon preservative of this character, none of the natural advantages of these preservatives are lost but-they are dissolved and more evenly distributed through-- out the cellular structure.

A further advantage of this chlorinated hydrocarbon preservative is the fact thatthe-chlorination has the effect of partially polymerizing the hydrocarbons to produce a wax-like waterproofing film upon or near the surface of the wood. This feature is particularly important in connection with the impregnation of wood blocks and building materials subjected to atmospheric weathering conditions. 7

Briefly, then, the novelty in the present process lies primarily in the use of high sulphur containing hydrocarbon, oils, such as the Lima, Persian or Mexican oils, chlorinated prior to impregnation or subsequent to impregnation in the wood or the use of a separate fraction of such oils separated preferably by cracking. The cracked materials, including the distillate, gas and residuum, have considerably better toxic properties and penetrating qualties than the original crude. The chlorinated hydrocarbons, including the crude as well as the cracked products, can be 'used in any of the well known standard treating processes such as the full cellor empty cell process.

I claim as my invention:

1. A process of preserving wood which .comprises the steps of impregnating the wood with a halogenated hydrocarbon having a natural sulphur content sufficient to give it toxic properties, and imposing thereon a pressure of a halogen gas.

2. A process of preserving wood which comprises the steps of impregnating the wood with a halogenated hydrocarbon having a natural sulphur content sufiicient to give it toxic properties, and imposing there- ,on a pressure of hydrocarbon gas.

ALFRED OBERLE. 

